Thyroid neoplasm is a neoplasm or tumor of the thyroid. It can be a benign tumor such as thyroid adenoma, or it can be a malignant neoplasm (thyroid cancer), such as papillary, follicular, medullary or anaplastic thyroid cancer. Most patients are 25 to 65 years of age when first diagnosed; women are more affected than men. The estimated number of new cases of thyroid cancer in the United States in 2023 is 43,720 compared to only 2,120 deaths. Of all thyroid nodules discovered, only about 5 percent are cancerous, and under 3 percent of those result in fatalities.
Diagnosis
The first step in diagnosing a thyroid neoplasm is a physical exam of the neck area. If any abnormalities exist, a doctor needs to be consulted. A family doctor may conduct blood tests, an ultrasound, and nuclear scan as steps to a diagnosis. The results from these tests are then read by an endocrinologist who will determine what problems the thyroid has.
Hyperthyroidism and hypothyroidism are two conditions that often arise from an abnormally functioning thyroid gland. These occur when the thyroid is producing too much or too little thyroid hormone respectively. As thyroid cancer can take up iodine, radioactive iodine is commonly used to treat thyroid carcinomas, followed by TSH suppression by high-dose thyroxine therapy.
Nodules are of particular concern when they are found in those under the age of 20. The presentation of benign nodules at this age is less likely, and thus the potential for malignancy is far greater.
Classification
Thyroid neoplasm might be classified as benign or malignant.
Benign neoplasms
Thyroid adenoma is a benign neoplasm of the thyroid. Thyroid nodules are very common and around 80 percent of adults will have at least one by the time they reach 70 years of age. Approximately 90 to 95 percent of all nodules are found to be benign.
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File:Histopathology of carcinoma of the thyroid with Ewing family tumor elements, and intrathyroid thymic carcinoma.jpg|Carcinoma of the thyroid with Ewing family tumor elements (CEFTE) disclosing solid nests of small cells with regular, round nuclei, and nests of papillary thyroid carcinoma (PTC) (a). This case is from a 17-year-old female patient with bilateral involvement of the thyroid by a malignant thyroid teratoma (b); the tumor discloses nests of small cells, rich stroma with chondroid appearance and an epithelial-tubular component. Mixed medullary and papillary thyroid carcinoma (c); the medullary thyroid carcinoma component stained positively for calcitonin mRNA while the PTC (follicular variant) component was negative (d). Intrathyroid thymic carcinoma (ITC) also known by the acronym (CASTLE) showing positivity for CD5 (inset) (e). Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a lobulated tumor composed of spindle cells and epithelioid cell component with glands, mucinous cysts, and/or squamous nests (f and g)
File:Histopathology of follicular patterned medullary thyroid carcinoma, and intrathyroidal parathyroid tissue.jpg|Follicular patterned medullary thyroid carcinoma (MTC) (a). In this other follicular patterned MTC (b), there are several calcifications simulating psammoma bodies (inset) and positivity for calcitonin (c). Intrathyroidal parathyroid tissue (d). The microscopic aspect of an intrathyroidal parathyroid adenoma is similar to eutopic parathyroid adenomas (e). Intrathyroidal parathyroid adenoma expressing chromogranin A (f) and PTH (g). Calcitonin-negative medullary thyroid carcinoma (h) showing positivity for CGRP (i). Paraganglioma (j) typically shows negativity for calcitonin and S100-positive sustentacular cells (inset)
Radioactive iodine-131 is used in patients with papillary or follicular thyroid cancer for ablation of residual thyroid tissue after surgery and for the treatment of thyroid cancer. Patients with medullary, anaplastic, and most Hurthle cell cancers do not benefit from this therapy.